The invention is based on an automatic drive slip regulating unit for motor vehicles or the like as defined hereinafter. Drive slip regulating units, or propulsion regulating devices, are used for slowing spinning drive wheels back down again by actuating their wheel brakes. This spinning is detected for instance by wheel rpm sensors, which are already used in the known anti-skid system. An automatic drive slip regulating unit of this kind is known for instance from German Pat. No. 31 27 301. There, a pressure intensifier that includes a floatingly supported plunger set into motion by an auxiliary pressure source is incorporated into a brake line between the master brake cylinder and the anti-skid system. This propulsion regulating device has the disadvantage, first, that it is integrated directly into the brake line and accordingly affects the normal braking process. Furthermore, when a plurality of brake circuits are present, one such propulsion regulating device must be provided for each individual brake circuit. Leaks or improper restoration of the plunger are not detected and so can cause considerable disruptions in the normal braking process.